Certain physical phenomena can be characterized by time-varying relationships, some of which may contain repetitive features. On occasion, one may wish to perform an act at a specific point in time, perhaps upon the occurrence of a particular feature. One particular application for this lies in medical imaging.
In imaging applications such as magnetic resonance imaging (MRI), computerized tomographic (CT) scanning, ultrasound, and positron emission tomography (PET), a series of related images should ideally be taken at the point where the heart (or other anatomy of interest) is in a relatively constant posture. This condition can be assured by synchronizing the imaging with a fixed point or phase in the heartbeat cycle. For example, the electrocardiogram (ECG) signal, specifically the R-wave within the QRS event in the ECG signal provides such a reference point, as it occurs when the ventricles are contracted.
Known methods for detecting the occurrence of an event often suffer from a processing delay. By the time such methods indicate that an event has occurred, that event has passed, and the anatomy may have undergone a significant change in position or posture. Preferably, the trigger should immediately follow the occurrence of the event. By predicting the signal some interval of time in advance of when the event will occur, one can compensate for the delay in the event detection process.